System of non-interchangeability for circuit protective devices on an electrical panelboard



June 13; 1967 DEVICES ON AN Filed STANBACK 3,325,693

SYSTEM OF NON-INTERCHANGEABILITY FOR CIRCUIT PROTECTIVE ELECTRICAL PANELBOARD Oct. 23, 1965 United States Patent SYSTEM OF NON-INTERCHANGEABILITY FOR CIRCUIT PROTECTIVE DEVICES ON AN ELEC- TRICAL PANELBOARD Harris I. Stanback, Lexington, Ky., assiguor to Square D Company, Park Ridge, 11]., a corporation of Michigan Filed Oct. 23, 1965, Ser. No. 503,892 4 Claims. (Cl. 317-119) This invention relates generally to electrical panelboards or load centers, and to circuit breakers and fusible tively with three different mounting clips adapted to receive a mounting rail, and a rejection bracket associated with the mounting rail may be modified to present three different configurations, each configuration of the rejection bracket enabling it to receive or cooperate with a different one of the mounting clips andto reject the other two. I i

In the drawings, FIG. 1 is an exploded perspective view of a mounting pan of an electrical panelboard and portions of the casings of three circuit breakers or fusible units of different ratings, the mounting pan having a beaded mounting rail and a rejection bracket constructed in accordance with the invention and the circuit breakers or fusible units respectively having different mounting clips constructed inaccordance withthe invention;

FIG. 2 is a sectional view of the mounting pan taken generally along line 2-2 of FIG. 1 and showing the mounting clip of the left-hand circuit breaker or fusible uni-t of FIG. 1 in place on the mounting rail, it being assumed that the .center and right-hand circuit breakers or fusibleunits of FIG. 1 are also in place on the panelboard and directly aligned with and behind the circuit breaker or fusible unit shown;

FIG. 3a is a fragmentary sectional view taken generally along line 3-3 of FIG. 2 and showing the mounting clip of the left-hand circuit breaker or fusible unit of FIG. 1; s

FIG. 3b is a fragmentary sectional view taken generally along line 3-3 of FIG. 2 and showing the mounting clip of the center circuit breaker or fusible unit of FIG. 1;

FIG. 4a is a fragmentary sectional view taken generally along line 4-4 of FIG. 2 and showing the left-hand circuit breaker or fusible unit of FIG. 1;

FIG. 4b is a fragmentary sectional view taken generally along line 44 of FIG. 2 and showing the center circuit breaker or fusible unit of FIG. 1;

FIG. 40 is a fragmentary sectional view taken generally along line 44 of FIG. 2 and showing the right-hand circuit breaker or fusible unit of FIG. 1; and

FIG. 5 is a perspective view of the mounting clip of the center circuit breaker or fusible unit of FIG. 1 before it is assembled in the casing thereof.

This invention is an improvement of the system of non-interchangeability disclosed in US. Patent No. 3,065,386. FIG. 1 shows portions of the casings of three circuit breakers or fusible units 10, 11, and 12 having different ratings and different mounting clips. As circuit breakers, they may be of the types shown in US. Patents Nos. 2,902,560, 3,134,051, and 3,061,697. As fusible units, they may be of the types disclosed in copending applications, Ser. No. 398,637, filed Sept. 23, 1963, Ser.

3,325,693 Patented June 13, 1967 No. 420,570, filed Dec. 23, 1964, and Ser. No. 423,680, filed Jan. 6', 1965, now Pat. No. 3,284,598, issued Nov. 8, 1966, all assigned to the assignee of the present invention. Hereinafter, the circuit breaker units or fusible units 10, 11, and 12 will be referred to simply as units. The units 10, 11, and 12 are provided adjacent one end respectively with resilient mechanical mounting clips 14, 15, and 16 adapted to fit over a mounting rail 18a formed as a beaded edge portion of a flange 18b of a generally fl'at mounting pan 18 of a mounting pan assembly normally secured to a rear wall portion of a box (not shown) to form an electrical panelboard or load center. Riveted or otherwise secured to the flange 18b is a rejection bracket 20 which cooperates with themounting clips 14, 15, and 16 to provide the improved system of non-interchangeability. In addition to the mounting pan 18 and the rejection bracket 20, the mounting pan assembly includes an insulating base (not shown) having a pair of bus bars (not shown) mounted thereon, as disclosed in copending application, Ser. No. 494,854, filed Oct. 11, 1965, and now Pat. No. 3,312,874, issued April 4, 1967, and the units 10, 11, and 12 are provided adjacent the other end respectively with plug-in terminal jaws (not shown) adapted respectively to plug on one of the bus bars. 1

The bracket 20 is generally L-shaped in cross section, but a free end portion 20a of a longer side portion 20b is reversely curled over to extend back generally parallel to the remainder of the longer side portion 2012 on the opposite side thereof from a shorter side portion 20c which is secured to the flange 18b. The side portion 20b is provided with a pair of sheared tongues 20d for each space on the electrical panel board or load center in which one of the units 10, 11, or 12 may be mounted. The sheared tongues 20d are adapted to be bent outwardly so as to extend away from the side portion 20b oppositely to the sideportion 200, a tool such. as described in US. Pat. No. 3,115,053 and available only to authorized persons being required to so modify the rejection bracket 20 when the mounting pan 18 is in 'a box of an electrical panelboard. The reversely curled free end portion 20a prevents the tongues 204 from being bent beyond a predetermined angle, while an upper face of the side portion 200 prevents them from being bent in the other direction, as explained in the aforementioned US. Pat. No. 3,065,386.

The mounting clips 14, 15, and 16 respectively include inner jaw port-ions 14a, 15a and 16a and outer jaw portions 14b, 15b, and 16b between which the mounting rail 18a is received when the units 10, 11, 12 are mounted. Further, the outer jaw portions 14b, 15b, and 16b are pro- .vided respectively with pairs of prong-like extensions 14c and 14a, 15c and 15d, and and 16d, the extensions 14d, 15c, 16c, and 16d being substantially identical to each other, generally straight and generally parallel to the flange 18b when the units 10, 11, and 12 are mounted, and the extensions 14c and 15d being substantially identical to each other and bent outwardly to extend generally perpendicularly to the flange 18b when the units 10, 11, and 12 are mounted.

As best shown in FIGS. 3m and 3b, the portion 20a of the rejection bracket 20 is provided with a plurality of notches 20'e to provide clearance for the free end portions of extensions such as extensions 14c and 15d, the notches 20e being spaced longitudinally of the rejection bracket 20. The notches 20a are made narrower than the tongues 20d to insure that the portion 20a of the rejection bracket 20 will stop the tongues 20d in proper position as they are bent away from the portion 20b, and opposite edge portions of the free end portions of the extensions 14c and 15d are cut away as shown for easy reception within the notches 20c.

The unit 12 has the highest current rating. For example, the unit 12 might be rated at 100 amperes. One of the units and 11 has an intermediate current rating, and the other has the lowest current rating. For example, the unit 10 might be rated at 30 amperes and the unit 11 at 60 amperes, or vice-versa. The non-interchangeability system of this invention insures that when an authorized person has first modified the rejection bracket 20 so that it will receive a unit 10 in a particular space on the electrical panelboard or load center, and then later modifies it so that it will receive a unit 11 in that space, or vice-versa, an unauthorized person will not be able to readily substitute a higher rated unit 12 in that space. Thus, if in a particular space one tongue 20d of the particular pair has been bent so as to accommodate an extension 14d, as in FIGS. 1 and 3a, so that a unit 10 may be mounted in that space, and later the other tongue 20d of the particular pair is bent so as to accommodate an extension 15c of a unit 11, were it not for the ingenious arrangement of this invention, an unauthorized person could mount a higher rated unit 12 in that space, as in FIGS. 1 and 46 where both tongues d of a particular pair are bent to accommodate the two straight prongs 16c and 16d of a unit 12. However, in accordance with this invention, if in a particular space the rejection bracket 20 has been modified by the bending of one tongue 20d of the particular pair to permit mounting of a unit 10, and it is later decided by an authorized person that a unit 11 should be mounted in that space, not only must the other tongue 20d of the particular pair be bent outwardly to accommodate the extension 15c, but the first tongue 20d must be bent back to its original position so as not to interfere with the outwardly bent extension 15d, and having been bent back, it would then interfere with the straight prong 16d of a unit 12 to prevent mounting thereof by an unauthorized person. In short, because of the outwardly bent extensions 14c and 15d, the mounting of either a unit 10 or a unit 11 in a particular space requires that at least one of the tongues 20d of the particular pair be in its original unbent position so that a unit 12 cannot be accommodated without further modification of the rejection bracket 20 by an authorized person having the proper tool.

I claim:

1. In an electrical panelboard having a mounting space in which a circuit protective unit may be mounted, a system of non-interchangeability for three circuit protective units respectively of relatively high, low, and intermediate current ratings, said system comprising three mounting clips of different configurations secured respectively to said units and adapted to mount said units selectively on said panelboard in said mounting space, and rejection means on said panelboard disposed in said mounting space, said rejection means being modifiable to present three different configurations in each of which said rejection means is cooperable with only one of said mounting clips to permit mounting of the respective unit on said panelboard in said mounting space and interferable with the other two of said mounting clips to prevent mounting of either of the other two units on said panelboard in said mounting space.

2. A system of non-interchangeability as claimed in claim 1, wherein said panelboard includes a generally fiat mounting pan having a mounting rail receivable in said mounting clips, said rejection means comprises a rejection bracket disposed adjacent said mounting rail and having a pair of sheared tongues, each of said tongues being bendable to dispose it either in a position in which it is generally parallel to said mounting pan or in a position in which it is generally perpendicular to said mounting pan, and each of said mounting clips includes a pair of extensions, both extensions of the mounting clip of a first of said units being generally perpendicular to said mounting pan when said first unit is mounted on said panelboard in said mounting space, one extension of the mounting clip of each of a second and a third of said units being generally perpendicular to said mounting pan and the other extension of the mounting clip of each of said second and third units being generally parallel to said mounting pan when said second and third units are selectively mounted on said panelboard in said mounting space and corresponding extensions of the mounting clips of said second and third units being reversed from each other with respect to being perpendicular or parallel to said mounting pan.

3. A system of non-interchangeability as claimed in claim 2, wherein said first unit is the one with the highest current rating.

4. A system of non-interchangeability as claimed in claim 1, wherein each of said mounting clips includes a pair of extensions either of a first type which is disposed in a first position with respect to the panelboard when the respective unit is mounted on the panelboard in said mounting space or of a second type which is disposed in a second position with respect to the panelboard when the respective unit is mounted on the panelboard in said mounting space, and said rejection means includes a pair of movable portions respectively disposable either in a first position or in a second position with respect to said panelboard, each of said movable portions when in the first of its said positions accommodating an extension of said first type and rejecting an extension of said second type and when in the second of its said positions accommodating an extension of said second type and rejecting an extension of said first type.

References Cited UNITED STATES PATENTS 2,916,675 12/1959 Middendorf 317-119 3,065,386 11/1962 King et al. 317--119 3,194,906 7/1965 Lewis et al. 317101 X ROBERT K. SCHAEFER, Primary Examiner.

M. G INSBURG, Assistant Examiner, 

1. IN ELECTRICAL PANELBOARD HAVING A MOUNTING SPACE IN WHICH A CIRCUIT PROTECTIVE UNIT MAY BE MOUNTED, A SYSTEM OF NON-INTERCHANGEABILITY FOR THREE CIRCUIT PROTECTIVE UNITS RESPECTIVELY OF RELATIVELY HIGH, LOW, AND INTERMEDIATE CURRENT RATINGS, SAID SYSTEM COMPRISING THREE MOUNTING CLIPS OF DIFFERENT CONFIGURATIONS SECURED RESPECTIVELY TO SAID UNITS AND ADAPTED TO MOUNT SAID UNITS SELECTIVELY ON SAID PANELBOARD IN SAID MOUNTING SPACE, AND REJECTION MEANS ON SAID PANELBOARD DISPOSED IN SAID MOUNTING SPACE, SAID REJECTION MEANS BEING MODIFIABLE TO PRESENT THREE DIFFERENT CONFIGURATIONS IN EACH OF WHICH SAID REJECTION MEANS IS COOPERABLE WITH ONLY ONE OF SAID MOUNTING CLIPS TO PERMIT MOUNTING OF THE RESPECTIVE UNIT ON SAID PANELBOARD IN SAID MOUNTING SPACE AND INTERFERABLE WITH THE OTHER TWO OF SAID MOUNTING CLIPS TO PREVENT MOUNTING OF EITHER OF THE OTHER TWO UNITS ON SAID PANELBOARD IN SAID MOUNTING SPACE. 